function checkLoginForm(form)
{
    var errorMessage = '';

    errorMessage += checkUserUsername();
    errorMessage += checkUserPassword();

    if (errorMessage != '')
    {
        alert("Form Error:\n" + errorMessage);
        return false;
    }

    return true;
}

function checkUserUsername()
{
    var errorMessage = '';

    document.getElementById('username').value = trim(document.getElementById('username').value);
    fieldValue = document.getElementById('username').value; 
    if (fieldValue == '')
    {
        errorMessage = "    - You must enter a username.\n";
    }

    return errorMessage;
}

function checkUserPassword()
{
    var errorMessage = '';

    fieldValue = document.getElementById('password').value;
    if (fieldValue == '')
    {
        errorMessage = "    - You must enter a password.\n";
    }

    return errorMessage;
}